The proposed study presents a plan for the investigation of the effects of chronic, intensive marihuana use on female reproductive physiology. Thirty healthy women between the ages of 18 and 30 who have used marihuana at least 4 days a week for a minimum period of six months will be compared with a group of thirty healthy women who have not used marihauna and are matched with the marihuana-using subjects on the basis of age, marital status, and pregnancy history. The criteria for selection of all study subjects include no use of other illicit drugs in the preceding 6 months, no use of oral contraceptives in the preceding 18 months, no history of endocrine disease or infertility, and menarche prior to age 16. Evaluation of each subject will begin with an interview to elicit a medical, sexual, and drug use history and a complete physical examination. Subjects will be studied for two complete menstrual cycles with a daily record kept of basal body temperature, sexual activity, marihuana use, alcohol ingestion, stressful events, and intercurrent health problems. Blood samples will be taken on days 1, 5, 10-20, and 30 of each menstrual cycle. Estrone, estradiol 17-B, progesterone, testosterone, luteinizing hormone, follicle stimulating hormone, and prolactin will be measured by highly specific radioimmunoassay techniques. Blood samples will also be measured for growth hormone concentration by radioimmunoassay and cortisol will be measured by a competitive protein binding method, as checks on stress and non-reproductive endocrine status. If hormonal analysis, basal body temperature pattern, and vaginal cytology all indicate anovulation, endometrial biopsy will be performed at the end of the subsequent cycle. Women using marihuana who are anovulatory will be asked to abstain from marihuana use for two months to evaluate ovulatory mechanisms in the absence of drug effects. Data derived from this study will allow an assessment of marihuana effects on the normal hormonal sequence of the menstrual cycle, on the occurrence of ovulation, on prolactin dynamics, and on sexual functioning in women.